The goal of The Johns Hopkins University EMCRO is to develop and implement an experimental quality assurance program at the Columbia Medical Plan. The proposed approach to quality assessment focuses on those aspects of health care delivery especially important in a health maintenance organization where the population served is known, namely, accessibility to care, effectiveness of care, and efficiency of services. Accessibility is measured in terms of the length of time members must wait between contacting the Clinic for care and obtaining it. Effectiveness is measured both in terms of patient outcome(i.e., patient-reported problem status, knowledge, satisfaction, compliance, and biologic outcomes when indicated), as well as in terms of medical care process. Efficiency is examined in terms of relationships between resources used and outcomes achieved. The approach is population-based in that these aspects of quality are assessed, to the extent possible, in a defined population, including both utilizers and non-utilizers of services. The model assumes that the development of a meaningful quality assurance system can best occur in a stepwise, incremental fashion, i.e., that quality assurance occurs in a series of rounds when data are gathered, instruments and measures tested, results reported to a quality assurance committee, and the utility of the measures for identifying problems in delivery of care examined. A subsequent round then builds on what is learned, both substantively and methodologically, and tests the impact of any changes made on the basis of the results of the previous round.